1. Field of the Invention
The present invention relates generally to agricultural planters. In particular, the present invention relates to scraper systems for gauge wheels of agricultural planters.
2. Description of the Related Art
Scrapers have proven to be a valuable tool in removing mud and moist soil from planter gauge wheels and for preventing a buildup of moist soil mixed with trash. This is frequently caused by the application of liquid fertilizer just ahead of the gauge wheel. The fertilizer is generally dropped into a furrow formed by a coulter. This results in moist soil being deposited on the surface by the coulter, and then the moist soil sticks to the gauge wheel tire along with trash. A build up on the tire affects the uniformity of planting depth and the uniformity of emergence, which agronomists have determined to be a major factor in yields.
Most scraper blades on the market are made of steel. They are held close to or against the tire surface of the gauge wheel. The scraping edge of the blades generally have a scalloped shape similar to a tire profile. At least one manufacturer provides a flexible plastic blade to improve the contact between the blade and tire.
Blades are usually placed so that the scraping edge is basically parallel to the axis of rotation of the gauge wheel. The plane of the blade is generally leaned away from the unscraped tire surface to allow the scraping edge to fit the tire profile closer and to more effectively deflect the mud or buildup away from the tire. Some scrapers can be adjusted in their own plane to improve the contact between the blade and tire.
The Applicant previously developed an adjustable scraper assembly having a triple adjusting clamp, which is described in U.S. Pat. No. 7,730,962 B1 and illustrated in FIGS. 1 to 3 of the present application. The triple adjusting clamp 100 shown in FIGS. 1 and 2 allows the scraper blade 101 to be infinitely adjustable. The content of the '962 patent is incorporated herein by reference to provide additional background information for the present application.
To achieve optimum performance, scraper blades must be positioned for minimum clearance or maximum contact with the gauge wheel tire. The purpose is to minimize void areas between the blade and the tire as these will allow small pieces of leaves and stems to bend over the edge of the scraper and accumulate. This is termed “hair pinning.” Sometimes the accumulation can be enough that the scraper no longer functions. Excessive pressure between the blade and wheel due to trash build up can prevent the wheel from turning.
However, setting the blade close to the tire almost assures that the blade will rub the tire, at least intermittently. This introduces the possibility of two other problems. The first comes about because gauge wheel tires generally are not very accurate. There almost always is a high spot or hump in the surface of the tire. When the scraping edge of the scraper blade is approximately horizontal across the width of the tire, this hump will contact the blade along its entire width which requires significant energy to push the tire past the scraper blade. The second possible problem is that the scraping edge could gouge into the surface of the tire.
The result would be that the gauge wheel would stop turning or the support rod would slip at both the top and bottom clamping points and the blade would swing rearward.
Complicating the situation is the fact that there are at least three different gauge wheel tire profiles currently being manufactured, and additional tire profiles used on earlier planters.
There is a need in the industry for an improved scraper system for gauge wheels for agricultural planters.